Surface normal optical interconnections can provide high density, high bandwidth communication between electronic components. One technology used to achieve this involves attaching a two-dimensional array of GaAs Multiple Quantum Well ("MQW") diodes as light detectors and modulators onto a prefabricated silicon VLSI chip using a flip-chip bonding technique, more fully described in Goossen, K. W. et al., "GaAs MQW Modulators Integrated with Silicon CMOS," IEEE Photonics Technology Letters p. 360-62 (April 1995), hereby incorporated by reference as if fully set forth herein. This technology can be used to fabricate complex, high density silicon optoelectronic VLSI circuits, as described in Goossen, K. W., et al., "Method of Designing an Electronic Integrated Circuit with Optical Inputs and Outputs," U.S. patent application Ser. No. 08/403,326, filed on May 14, 1995.
One of the key features of this technology is that the optical input/output interfaces are arranged over the two dimensional surface of the chip, rather than along its perimeter, thereby allowing for a greater number of channels to interface with the chip than otherwise possible. However, to take advantage of this technology, the optical system that delivers the data to the chip must access the chip along both dimensions of the chip surface.
Conventional optics can image onto a chip surface a two dimensional array of optical data channels between two optoelectronic chips. Computing and communication systems with multiple optoelectronic chips can be connected by precision optics provided the distances are small enough that optical alignment between the chips can be maintained. However, if the optical data signals are to be carried for more than a few meters the signals must be transported by optical fiber. Effective interconnection of such distant optoelectronic chips then requires efficiently coupling a two dimensional array of data signals into and out of optical fiber.
One method for providing two dimensional access to a chip is to use a two dimensional array of single mode optical fibers. This method has been used to deliver signals to a photonic ATM switch chip, as described in Lentine, A. L. et al., "Demonstration of an Experimental Single-Chip Optoelectronic Switching System," Procedings 1995 LEOS Annual Meeting (November 1995). However, whereas fabricating a one dimensional array of single mode optical fibers is fairly routine, as a result of the stringent alignment requirements between fibers, manufacturing a two dimensional fiber array with a desired accuracy is difficult and costly.